1. Field of the Invention
The present invention relates to an electronic hydraulic pressure control system. More particularly, the present invention relates to an electronic hydraulic pressure control system and a control method thereof, which can detect an error in differential pressure between a master cylinder and a wheel cylinder.
2. Description of the Related Art
In general, a hydraulic brake system of a vehicle is equipped with an ABS (Anti-lock Brake System), an ESP (Electronic Stability Program), and TCS (Traction Control System) for preventing wheels from slipping upon a braking operation, thereby improving performance of a brake device of the vehicle.
The ABS, ESP and TCS adjust pressure of a wheel cylinder according to pressure of a master cylinder, the state of road, a vehicle speed, and the like to control a slip of the vehicle and a vehicle posture.
The hydraulic brake system of the vehicle includes a master cylinder connected to a brake pedal and equipped with a pressure sensor, a wheel cylinder connected to front and rear wheels and equipped with a pressure sensor, and a plurality of solenoid valves for controlling hydraulic pressure supplied to the wheel cylinder. If the ABS, ESP and the TCS are not operated, the solenoid valves are not operated, so that differential pressure between the master cylinder and the wheel cylinder is constantly maintained. However, if the ABS, ESP and the TCS are operated, pressure of the master cylinder and the wheel cylinder may vary. Thus, it is necessary to control pressure of the master cylinder and the wheel cylinder such that differential pressure between the master cylinder and the wheel cylinder can be constantly maintained.
According to a conventional electronic hydraulic pressure control system, if the pressure control is not normally performed due to variation in peripheral environment and long-time use of the system, hydraulic liquid may be leaked from the master cylinder to the wheels and the hydraulic liquid is dumped when controlling pressure of the wheels. If the above situation is continued, the hydraulic liquid contained in the master cylinder may be continuously exhausted, so that the hydraulic solution contained in the master cylinder is depleted, causing malfunction of the braking operation. If the pressure control is not appropriately performed, a brake pedal is down for the purpose of safety.